[PATCH v3 11/13] memcg: allow a memcg with kmem charges to be destructed.
STALE5108d
REVIEWED: 1 (0M)
From: Glauber Costa <hidden>
Date: 2012-09-18 14:09:05
Also in:
linux-mm, lkml
Subsystem:
control group - memory resource controller (memcg), memory management, the rest · Maintainers:
Johannes Weiner, Michal Hocko, Roman Gushchin, Shakeel Butt, Andrew Morton, Linus Torvalds
Revision v3 of 4 in this series; 1 review trailer.
Revisions (4)
- v3 current
- v4 [diff vs current]
- v5 [diff vs current]
- v6 [diff vs current]
Because the ultimate goal of the kmem tracking in memcg is to track slab pages as well, we can't guarantee that we'll always be able to point a page to a particular process, and migrate the charges along with it - since in the common case, a page will contain data belonging to multiple processes. Because of that, when we destroy a memcg, we only make sure the destruction will succeed by discounting the kmem charges from the user charges when we try to empty the cgroup. Signed-off-by: Glauber Costa <redacted> Acked-by: Kamezawa Hiroyuki <redacted> CC: Christoph Lameter <redacted> CC: Pekka Enberg <penberg-bbCR+/B0CizivPeTLB3BmA@public.gmane.org> CC: Michal Hocko <redacted> CC: Johannes Weiner <redacted> CC: Suleiman Souhlal <redacted> --- mm/memcontrol.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index aada601..b05ecac 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c@@ -631,6 +631,11 @@ static void disarm_kmem_keys(struct mem_cgroup *memcg) { if (memcg_kmem_is_accounted(memcg)) static_key_slow_dec(&memcg_kmem_enabled_key); + /* + * This check can't live in kmem destruction function, + * since the charges will outlive the cgroup + */ + WARN_ON(res_counter_read_u64(&memcg->kmem, RES_USAGE) != 0); } #else static void disarm_kmem_keys(struct mem_cgroup *memcg)
@@ -3933,6 +3938,7 @@ static int mem_cgroup_force_empty(struct mem_cgroup *memcg, bool free_all) int node, zid, shrink; int nr_retries = MEM_CGROUP_RECLAIM_RETRIES; struct cgroup *cgrp = memcg->css.cgroup; + u64 usage; css_get(&memcg->css);
@@ -3966,8 +3972,17 @@ move_account: mem_cgroup_end_move(memcg); memcg_oom_recover(memcg); cond_resched(); + /* + * Kernel memory may not necessarily be trackable to a specific + * process. So they are not migrated, and therefore we can't + * expect their value to drop to 0 here. + * + * having res filled up with kmem only is enough + */ + usage = res_counter_read_u64(&memcg->res, RES_USAGE) - + res_counter_read_u64(&memcg->kmem, RES_USAGE); /* "ret" should also be checked to ensure all lists are empty. */ - } while (res_counter_read_u64(&memcg->res, RES_USAGE) > 0 || ret); + } while (usage > 0 || ret); out: css_put(&memcg->css); return ret;
--
1.7.11.4